Wireless suspension design to accommodate multiple drive designs

ABSTRACT

A wireless suspension design is described that can be used in varying types of drive designs. In one embodiment, a flex circuit is provided with at least two indicia to indicate where the flex circuit is to be bent when attaching it to a head stack assembly.

BACKGROUND OF THE INVENTION

The present application claims priority to U.S. App. No. 60/316,154filed on Aug. 28, 2001.

The present invention is directed to suspension designs in disk drives.More particularly, the present invention pertains to wireless suspensiondesigns that may be used in multiple drive designs.

Hard disk drives that utilize magnetic read/write heads are well-knownin the art. A common component of a hard disk drive is a head stackassembly (HSA). An HSA includes an actuator (which incorporates anE-block), a head gimbal assembly (HGA) and an actuator flex assembly.The flex assembly is a flex circuit that is typically attached to anintegrated circuit chip that processes data read from the disk and datato be written to the disk. The actuator flex assembly is connected tothe HGA. The end result for the HSA is that the magnetic head of the HGAis electrically connected to the integrated circuit chip.

A typical HGA includes a magnetic read/write head that is attached to orincorporated into a slider (which typically include an air bearingsurface to allow the head to “fly” over the moving disk). The slider isattached to a flexure, which provides support for the slider andcontrols the pitch and roll of the slider relative to the moving disk.The high speed rotation of a magnetic disk generates a stream of airflow or wind along its surface in a direction substantially parallel tothe tangential velocity of the disk. The air flow cooperates with theABS of the slider body which enables the slider to fly above thespinning disk. In effect, the suspended slider is physically separatedfrom the disk surface through this self-actuating air bearing. The ABSof a slider is generally configured on the slider surface facing therotating disk, and greatly influences its ability to fly over the diskunder various conditions.

As shown in FIG. 1 an ABS design known for a common catamaran slider 5may be formed with a pair of parallel rails 2 and 4 that extend alongthe outer edges of the slider surface facing the disk. Other ABSconfigurations including three or more additional rails, with varioussurface areas and geometries, have also been developed. The two rails 2and 4 typically run along at least a portion of the slider body lengthfrom the leading edge 6 to the trailing edge 8. The leading edge 6 isdefined as the edge of the slider that the rotating disk passes beforerunning the length of the slider 5 towards a trailing edge 8. As shown,the leading edge 6 may be tapered despite the large undesirabletolerance typically associated with this machining process. Thetransducer or magnetic element 7 is typically mounted at some locationalong the trailing edge 8 of the slider as shown in FIG. 1. The rails 2and 4 form an air bearing surface on which the slider flies, and providethe necessary lift upon contact with the air flow created by thespinning disk. As the disk rotates, the generated wind or air flow runsalong underneath, and in between, the catamaran slider rails 2 and 4. Asthe air flow passes beneath the rails 2 and 4, the air pressure betweenthe rails and the disk increases thereby providing positivepressurization and lift. Catamaran sliders generally create a sufficientamount of lift, or positive load force, to cause the slider to fly atappropriate heights above the rotating disk. In the absence of the rails2 and 4, the large surface area of the slider body 5 would produce anexcessively large air bearing surface area. In general, as the airbearing surface area increases, the amount of lift created is alsoincreased. Without rails, the slider would therefore fly too far fromthe rotating disk thereby foregoing all of the described benefits ofhaving a low flying height.

As illustrated in FIG. 2, a head gimbal assembly 40 often provides theslider with multiple degrees of freedom such as vertical spacing, orpitch angle and roll angle which describe the flying height of theslider. As shown in FIG. 2, a suspension 74 holds the HGA 40 over themoving disk 76 (having edge 70) and moving in the direction indicated byarrow 80. In operation of the disk drive shown in FIG. 2, an actuator 72moves the HGA over various diameters of the disk 76 (e.g., innerdiameter (ID), middle diameter (MD) and outer diameter (OD)) over arc75.

A preamplifier is typically connected to the head to supply writecurrents to the write head and receive currents from the read head. Thesuspension provides two functions: mechanical support and electricalconnection between the head and the preamplifier. Rather than usingphysical wires to connect the head to the preamplifier, metal traces onthe suspension are quite often used.

The preamplifier resides in a subassembly common referred to as theActuator Flex Preamp Assembly (AFPA). The preamplifier is usuallysoldered to a flexible circuit. This flexible circuit provides the areasto which the HGA traces will be connected to complete the circuitconnecting the preamplifier to the read and write elements of the head.

Generally, there are two types of HGAs—wired and wireless. A wired HGAis one where separate lead wires are connected between the flex circuitof the HSA and the read write head. A wireless HGA is one whereconductive traces are integrated with the flexure and provideconductivity between the flex circuit of the HSA and the read write headof the slider. In the art, there are typically two types of wirelesssuspensions. In the first type, such as trace suspension assemblies(TSAs) and circuit integrated suspension (CISs), traces are built thougha subtractive process (e.g., an etching operation) or through anadditive process (e.g., a plating or deposition process) on thestainless steel flexure, with an insulative layer between the trace andthe flexure. After the traces are set in place, the flexure can then bewelded to other parts of the suspension. In the second type, such asflex suspension assemblies (FSAs) and flex on suspension (FOS), thetraces are built on an insulation layer and then covered with anotherinsulation layer to form a flex circuit. This circuit is then attachedto the suspension with adhesive. Alternatively, an additional metallayer called a ground plane can be attached to the flex circuit beforeit is adhered to the suspension. In an FSA, the flexure is integratedwith a load beam and a mount plate along with the integrated traces forconnectivity.

Typically four traces are supplied for a single head: one pair for theconnection between the read head and the pre amplifier and one pair forthe connection between the write head and the preamplifier.

As seen from the above, there are various types of HGA and HSA designs.The designs that are selected depend on the disk drive underconsideration. Once the designs are selected, the flex circuit willrequire electical connection in the process of manufacturing HSAs. As isknown in the art, the flex circuit of the HGA usually reuires attachmentat two ends of the circuit. On one ende, the flex circuit will beattached to the side of the assembly that includes the slider's airbearing surfaces. For a wireless HGA like the so-called TSA suspension,bonding pads are provided adjacent to the slider which are soldered orotherwise electrically connected to the conductors of the flex circuit.On the other end of the HGA circuit, the traces will be attached toareas in the AFPA that will lead to the preamplifier. Because of theplacement of the integrated circuit chip, the flex circuit is usuallyattached to a side of the AFPA that is orthogonal to the surface of theHGA where the circuit is bonded. During manufacture, the flex circuit isusually bent at a 90 degree angle before attaching it to the AFPA.Because of differing dimensions for the various designs set forth above,manufacturers typically fabricate a variety of flex circuits specific tothe designs and/or the disk drives that contain the flex circuits. Sucha process leads to the potential for increased costs in manufacture andlost costs in unneeded flex circuits.

SUMMARY OF THE INVENTION

According to an embodiment of the present invention, a flex circuit ispresented that is designed to accommodate multiple drive designs. In oneembodiment, the flex circuit includes two or more bending lines so thatthe flex circuit can be bent at two or more different locationsdepending on the disk drive assembly being used. Doing so may result ina significant reduction in manufacturing costs.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a slider device with a read/write headthat is known in the art.

FIG. 2 is a perspective view of a disk drive device that is known in theart.

FIG. 3 is an overhead view of a suspension assembly utilizing a flexcircuit constructed according to an embodiment of the preset invention.

FIG. 4 is a closer view of a feature of the flex circuit of FIG. 3.

FIG. 5 is a side view of a suspension in a first disk drive using theflex circuit of FIG. 3.

FIG. 6 is a side view of a suspension in a second disk drive using theflex circuit of FIG. 3.

DETAILED DESCRIPTION

Referring to FIG. 3, an overhead view of a suspension assembly 100 isshown using a flex circuit constructed according to an embodiment of thepresent invention. In this embodiment of the present invention, the flexcircuit 101 includes a substrate made of polyamide and conductors madeof copper, but is not limited to these materials. As described below theflex circuit of the present invention has a design that allows it to beused with multiple disk drive designs.

Referring to FIG. 4, a close up view is shown of a feature of the flexcircuit shown in FIG. 3. As seen in FIG. 4, the flex circuit 101includes a plurality of indicia to indicate where the flex circuit is tobe bent (e.g., on a suspension assembly). In this example, the indiciaincludes a pair of notches in the substrate material of the flexcircuit. Accordingly, the flex circuit is to be bent along a lineindicated by a first pair of notches A or a second pair of notches Bdepending on the design of the disk drive.

Referring to FIGS. 5 and 6, the flex circuit of FIG. 3 is shown in itsbent condition for two disk drives. In FIG. 5, a first disk drive isshown, where the flex circuit is bent 90 degrees at the first pair ofindicia A prior to or after being attached to a suspension for thedrive. In FIG. 6, the flex circuit is bent 90 degrees at the second pairof indicia B prior to or after being attached to a suspension for thedrive.

While the present invention has been described with reference to theaforementioned applications, this description of the preferredembodiments is not meant to be construed in a limiting sense. It shallbe understood that all aspects of the present invention are not limitedto the specific depictions, configurations or dimensions set forthherein which depend upon a variety of principles and variables. Variousmodifications in form and detail of the disclosed apparatus, as well asother variations of the present invention, will be apparent to a personskilled in the art upon reference to the present disclosure. It istherefore contemplated that the appended claims shall cover any suchmodifications or variations of the described embodiments as fallingwithin the true spirit and scope of the present invention. For example,though the invention has been described with respect to a flex circuitthat attaches to a head assembly, it can be extended to trace suspensionassemblies that utilize flex circuits, as well.

1-10. (Cancelled)
 11. A method of manufacturing a suspension assemblycomprising: forming a flex circuit including a substrate; providingindicia on said substrate to indicate where the substrate is to be bent.12. The method of claim 11 further comprising: attaching said flexcircuit to a suspension assembly and bending said flex circuit at saidindicia.
 13. The method of claim 12 wherein in said forming operationsaid flex circuit includes a plurality of conductors.
 14. A method ofmanufacturing a suspension assembly comprising: forming substrate andconductors onto a flexure, said substrate including indicia to indicatewhere the substrate is to be bent.
 15. The method of claim 14 furthercomprising: attaching said flexure to a suspension assembly.
 16. Themethod of claim 15 further comprising: bending said substrate andconductors at said indicia.